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Thread: How long should a shock take?

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    Shpigford's Avatar
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    How long should a shock take?

    Wednesday afternoon I shocked my pool. There wasn't much green/algae, but FC was near 0 and the water was super cloudy.

    Since Wednesday afternoon I've done my best to keep FC at ~12 (though it's gotten as low as 8). It's been as high as 14.

    So, now it's Saturday and while the water certainly isn't green anymore, it's still very cloudy. It's been three days of shocking but no real visual results that things are getting better. Is that typical?

    Overnight FC loss has been ~2-3, but CC levels have been zero or maybe 0.2 or 0.3...certainly below 0.5.

    Here are my most recent tests (as of this evening):

    FC - 13.5
    CC - 0.6
    pH - 7.4
    TA - 80
    CH - 140
    CYA - 30
    22,000 gallon vinyl in ground with Hayward S244T sand filter and Hayward 3/4 hp Super Pump.

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    Mod Squad woodyp's Avatar
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    Re: How long should a shock take?

    Sand filters are fairly slow................so you're fairly typical. Running the filter 24/7 till it clears and backwashing as necessary? How about a full set of test numbers......especially your CYA level. Are you shocking per the CYA/Chlorine chart in pool school? If so..........fudge that shock level number a couple of ppm.
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    Mod Squad zea3's Avatar
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    Re: How long should a shock take?

    Could you post a current set of test results? That way we will know if you are hitting the correct shock level for your pool. Since the overnight FC loss is still > 1ppm, you need to keep the pool at shock level and keep the pump running 24/7.

    Sand filters will take a bit longer to filter out dead algae. You can help things along by adding some DE to the sand filter to increase filtration of finer particles.
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    Shpigford's Avatar
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    Re: How long should a shock take?

    Here are current test results:

    FC - 13.5
    CC - 0.6
    pH - 7.4
    TA - 80
    CH - 140
    CYA - 30

    I haven't backwashed because ~48 hours ago I added a ton of CYA (it was 0), so didn't want to wash any of that out. Is it okay to backwash now?

    And yes, I've been running the filter 24/7.
    22,000 gallon vinyl in ground with Hayward S244T sand filter and Hayward 3/4 hp Super Pump.

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    Re: How long should a shock take?

    If it has been 48 hours since adding your CYA, I think that you will be alright to do a backwash. That should be enough time.

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    Re: How long should a shock take?

    If the pool is slow to clear, then note that you can Add DE to a Sand Filter to make the filter more effective.
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